The present invention relates to a static screen for animated images.
Static devices are known that provide a view that is in relief or that is animated, and that are constituted by a set of lenses or prisms constituting a lens array associated with a xe2x80x9cprimaryxe2x80x9d image itself made up of points known as xe2x80x9cpixelsxe2x80x9d, said lens array enabling the eye of a spectator to see different subsets of said pixels depending on the postion of the eye relative to the device.
Each subset of pixels constitutes a different image which can be seen by the eye of the spectator from one or more different locations.
In the dispositions used for those known devices, the lenses or prisms are generally arranged in columns and the pixels that are to be seen through a column of lenses or prisms are situated in register with the column or lenses or prisms, and a set of pixels that is to be seen through a lens or prism is of a width that is smaller than or equal to the width of the lens or prism in question.
The resolution of the image seen by the spectator, which can be expressed in pixels per inch (and often written xe2x80x9cdots per inchxe2x80x9d or DPI) increases with decreasing width of each lens, and as a result the width of a set of pixels seen through a lens is limited. This narrow width limits the number of different images that can be seen by the spectator of such a known device.
Embodiments of the proposed screen make the following possible:
animated images can be viewed because it is possible to have a large number of successive images present;
images can be viewed in relief;
images can be viewed which are both animated and in relief, using a screen that has no moving parts, that is of simple design, and economical to manufacture.
The proposed device is a screen comprising a plurality of juxtaposed optical devices referred to as xe2x80x9celementary devicesxe2x80x9d, each of said elementary devices comprising:
an elementary lens 1 or equivalent optical system referred to as an xe2x80x9celementary lensxe2x80x9d; and
an elementary image 2 situated in register with said elementary lens, constituted by a set of points 2a, 2b, 2c, et seq. referred to as xe2x80x9cpixelsxe2x80x9d that the spectator can see through said elementary lens 1, the spectator seeing one or more different pixel(s) depending on the position of the spectator relative to the elementary lens 1,
the screen being characterized by the facts that:
the shape of said elementary image 2 is not identical to the projection of said elementary lens 1 onto the surface of the screen, but on the contrary is of mean height smaller than the projection of said elementary lens 1 onto the screen and of mean width greater than the projection of said elementary lens 1 onto the screen, thus having the effect that a portion of the elementary image is situated in register with a portion of an elementary lens that is adjacent to the elementary lens 1 under consideration; and
two adjacent elementary images are offset in height relative to each other so as to avoid overlapping; it being specified that the terms xe2x80x9cheightxe2x80x9d and xe2x80x9cwidthxe2x80x9d as used above and below relate to measurements made along respective ones of two arbitrary perpendicular axes referred to as the xe2x80x9cverticalxe2x80x9d axis and as the xe2x80x9chorizontalxe2x80x9d axis, both situated in the plane of the screen, neither of these axes necessarily being vertical or horizontal relative to the earth.
According to other characteristics of the invention:
said elementary image is inscribed in a rectangle of height (h) and width (l) defined by the following formulae:
h=(S/w)0.5xc3x97[D/(Dxe2x88x92F)]/K
l=(S/w)0.5xc3x97[D/(Dxe2x88x92F)]xc3x97K
S being the total surface area of the set of elementary lenses as projected onto the plane of the screen;
w being the total number of elementary lenses;
D being the distance between the eyes of the spectator and the plane containing the elementary images,
F being the distance between the focal plane of the elementary lenses and the plane containing the elementary images; and
K being an arbitrarily chosen coefficient greater than 1;
two adjacent elementary images are offset in height by the height of one elementary image;
the xe2x80x9chorizontalxe2x80x9d axis is parallel to the displacement axis of the spectator in a plane parallel to the plane of the screen, and the ratio K is equal to the square root of the ratio that exists between the width and the height of the rectangle constituted by orthogonally projecting onto the screen the geometrical locus of possible locations for the eyes of the spectator, said locus being referred to as the spectator""s viewing range;
the elementary lenses are lenses in the form of regular hexagons, each lens touching another lens on all six sides, the rows of lenses being inclined at an angle of 0.33 radians relative to the displacement axis of the spectator in a plane parallel to the plane of the screen, and said coefficient K being equal to 2.77;
each elementary lens is constituted by a centered lenticular system 5 and a prism 6;
the elementary lenses 1 are not offset vertically relative to one another, and the prism angle deflects light rays in such a manner that corresponding points of two elementary images 2a and 2b are seen by the spectator through the two corresponding elementary lenses 1a and 1b; 
the horizontally juxtaposed elementary lenses 1a and 1b are not offset vertically to each other, and the optical axes of said elementary lenses 1 are offset vertically in such a manner that corresponding points of two elementary images 2a and 2b are seen by the spectator through the two corresponding elementary lenses 1a and 1b; 
the elementary lens 1 is provided with a prism system 8 deflecting light rays towards spectators not situated in register with said elementary lens.
each elementary image 2 comprises, from one side edge to the other, and in order:
a) a set C(x,y)P(n) of points copied from a subset, of abscissa x and of ordinate y, of the primary image of rank n;
b) a set C(x,y)P(n+1) of points copied from a subset, of abscissa x and of ordinate y, of the primary image of rank n+1; and
c) so on, the abscissa x and the ordinate y of the elementary image being respectively equal to the abscissa x and the ordinate of the sets C,
it being specified that the term xe2x80x9cprimary imagesxe2x80x9d is used above and below to designate the images that are to be shown in succession to a spectator moving along the screen, and that the term xe2x80x9crankxe2x80x9d is used above and below with respect to a primary image to designate the chronological order in which said primary is to be seen by the spectator moving along the screen;
each elementary image 2 comprises, from one side edge to the other, and in order:
a) a set C(x,y)P(n) of points copied from a subset, of abscissa x and of ordinate y, of the primary image of rank n;
b) a set C(xxe2x88x921,y)P(n+1) of points copied from a subset of abscissa xxe2x88x921 and of ordinate y of the primary image of rank n+1; and
c) so on, the ordinate y of the elementary image being equal to the ordinate of the sets C;
the xe2x80x9cprimaryxe2x80x9d images serving to make the elementary images 2 are created by a motion picture camera which, while recording said primary images, describes a trajectory whose axis is substantially different from an axis parallel to the axis of the camera lens;
the camera is stationary and the subject to be filmed is situated on a turntable;
the elementary lenses 1 are Fresnel lenses;
the faces of the elementary lenses 1 situated on the same side as the spectator are plane and together they constitute the face of the screen situated on the same side as the spectator;
the elementary lenses 1 are obtained by molding plates of transparent material, each comprising a large number of elementary lenses;
each elementary lens comprises a lens 5 having a plane face situated on its side remote from the spectator, said face being situated in a plane referred to as the xe2x80x9cuniquexe2x80x9d plane which is identical for all of the elementary lenses, and a transparent plate 12 having different optical characteristics is stuck to the lenses 5, adhesion taking place in the said unique plane, and the elementary images being applied directly to the rear face 3 of said transparent plate 12; and
the screen includes an image acquisition device, e.g. a set of photoelectric sensors or a photographic film, replacing the set of elementary images 3, and is situated on the rear face of a camera, comprising:
a) a conventional photographic lens 13 mounted on a horizontal slideway 15; and
b) a shutter enabling the lens to make multiple successive exposures.